1. Field of the Invention
The present invention relates to a method for producing a modified propylene polymer, and particularly, to a method which can produce a modified propylene polymer which has a wide molecular weight distribution and is superior in fluidity.
2. Description of the Related Art
Propylene polymers are used in a wide variety of applications such as automotive components and components of household electric appliances due to their superior mechanical properties. It is known to modify a propylene polymer by grafting an unsaturated carboxylic acid or its derivative to the propylene polymer.
For example, JP 9-3140 A discloses a method for producing a graft modified propylene polymer by graft copolymerizing a polar monomer to a propylene homopolymer having an intrinsic viscosity of from 0.1 to 20 dl/g.
JP 2002-20436 A discloses a method for producing a modified polypropylene resin by melt-kneading an ultra high molecular weight crystalline polypropylene resin having an intrinsic viscosity of from 5 to 15 dl/g with a mixture including an ethylenically unsaturated bond-containing monomer and an organic peroxide.
However, modified propylene polymers obtained by the methods disclosed in the above-cited references do not always have high molecular weight distributions and a further improvement in their fluidity has been demanded.